Carbon-dioxide
Ammonia
Freon-11
Freon-22
difference in temperature of the cold water and atmospheric temperature
difference in temperature of hot water entering and cold water leaving
amount of heat thrown away by the cooling tower in kcal/hr
difference in temperature of the cold water leaving the cooling tower and the wet bulb temperature of surrounding air
Cross charged valve
Straight charged valve
Pilot operated solenoid valve
Three way mixing valve
Direct system
Indirect system
Cross system
Isolated system
Soap and water
Burning candle
Sulphur sticks
Halide torch